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Schaubeder JB, Spirk S, Fliri L, Orzan E, Biegler V, Palasingh C, Selinger J, Bakhshi A, Bauer W, Hirn U, Nypelö T. Role of intrinsic and extrinsic xylan in softwood kraft pulp fiber networks. Carbohydr Polym 2024; 323:121371. [PMID: 37940269 DOI: 10.1016/j.carbpol.2023.121371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 08/31/2023] [Accepted: 09/06/2023] [Indexed: 11/10/2023]
Abstract
Xylan is primarily found in the secondary cell wall of plants providing strength and integrity. To take advantage of the reinforcing effect of xylan in papermaking, it is crucial to understand its role in pulp fibers, as it undergoes substantial changes during pulping. However, the contributions of xylan that is added afterwards (extrinsic) and xylan present after pulping (intrinsic) remain largely unexplored. Here, we partially degraded xylan from refined bleached softwood kraft pulp (BSKP) and adsorbed xylan onto BSKP. Enzymatic degradation of 1 % xylan resulted in an open hand sheet structure, while adsorption of 3 % xylan created a denser fiber network. The mechanical properties improved with adsorbed xylan, but decreased more significantly after enzymatic treatment. We propose that the enhancement in mechanical properties by adsorbed extrinsic xylan is due to increased fiber-fiber bonds and sheet density, while the deterioration in mechanical properties of the enzyme treated pulp is caused by the opposite effect. These findings suggest that xylan is decisive for fiber network strength. However, intrinsic xylan is more critical, and the same properties cannot be achieved by readsorbing xylan onto the fibers. Therefore, pulping parameters should be selected to preserve intrinsic xylan within the fibers to maintain paper strength.
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Affiliation(s)
- Jana B Schaubeder
- Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria
| | - Stefan Spirk
- Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria
| | - Lukas Fliri
- Department of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, FI-00076 Aalto, Finland
| | - Eliott Orzan
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| | - Veronika Biegler
- Institute for Materials Chemistry and Research, University of Vienna, Währinger Straße 42, 1090 Vienna, Austria
| | - Chonnipa Palasingh
- Department of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, FI-00076 Aalto, Finland
| | - Julian Selinger
- Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria; Department of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, FI-00076 Aalto, Finland
| | - Adelheid Bakhshi
- Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria
| | - Wolfgang Bauer
- Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria
| | - Ulrich Hirn
- Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria.
| | - Tiina Nypelö
- Department of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, FI-00076 Aalto, Finland; Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden.
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Tialiou A, Athab ZH, Woodward RT, Biegler V, Keppler BK, Halbus AF, Reithofer MR, Chin JM. Fabrication of graded porous structure of hydroxypropyl cellulose hydrogels via temperature-induced phase separation. Carbohydr Polym 2023; 315:120984. [PMID: 37230621 DOI: 10.1016/j.carbpol.2023.120984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 04/14/2023] [Accepted: 05/02/2023] [Indexed: 05/27/2023]
Abstract
A novel hydroxypropyl cellulose (gHPC) hydrogel with graded porosity has been fabricated, in which pore size, shape, and mechanical properties vary across the material. The graded porosity was achieved by cross-linking different parts of the hydrogel at temperatures below and above 42 °C, which was found to be the temperature of turbidity onset (lower critical solution temperature, LCST) for the HPC and divinylsulfone cross-linker mixture. Scanning electron microscopy imaging revealed a decreasing pore size along the cross-section of the HPC hydrogel from the top to the bottom layer. HPC hydrogels demonstrate graded mechanical properties whereby the top layer, Zone 1, cross-linked below LCST, can be compressed by about 50% before fracture, whereas the middle and bottom layers (Zone 2 and 3, respectively) cross-linked at 42 °C, can withstand 80% compression before failure. This work demonstrates a straightforward, yet novel, concept of exploiting a graded stimulus to incorporate a graded functionality into porous materials that can withstand mechanical stress and minor elastic deformations.
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Affiliation(s)
- Alexia Tialiou
- University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry, Währinger Str. 42, 1090 Vienna, Austria; University of Vienna, Vienna Doctoral School in Chemistry (DoSChem), Währinger Str. 42, 1090 Vienna, Austria
| | - Zahraa H Athab
- University of Babylon, College of Science, Department of Chemistry, Hilla, Iraq; University of Babylon, College of Science, Environmental Research and Studies Center, Hilla, Iraq
| | - Robert T Woodward
- University of Vienna, Faculty of Chemistry, Institute of Materials Chemistry and Research, Währinger Str. 42, 1090 Vienna, Austria
| | - Veronika Biegler
- University of Vienna, Faculty of Chemistry, Institute of Materials Chemistry and Research, Währinger Str. 42, 1090 Vienna, Austria
| | - Bernhard K Keppler
- University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry, Währinger Str. 42, 1090 Vienna, Austria; University of Vienna and Medical University of Vienna, Research Cluster "Translational Cancer Therapy Research", Währinger Str. 42, 1090 Vienna, Austria
| | - Ahmed F Halbus
- University of Babylon, College of Science, Department of Chemistry, Hilla, Iraq
| | - Michael R Reithofer
- University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry, Währinger Str. 42, 1090 Vienna, Austria.
| | - Jia Min Chin
- University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry-Functional Materials, Währinger Str. 42, 1090 Vienna, Austria.
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